Rotary piston engine with auxiliary chamber on its casing

ABSTRACT

A rotary-piston engine in which two pairs of pistons rotate in a cylindrical casing, one pair rotating at uniform speed, the other at cyclically varying speed so that the pistons define expanding and contracting chambers therebetween, air of combustion is drawn through an intake port on one axial level, and combustion gases are discharged through an exhaust port on another level. A spark plug and a fuel injection nozzle are mounted in an auxiliary chamber outside the casing cavity which communicates with the auxiliary chamber through an aperture circumferentially divided by a partition, the total circumferential width of the aperture being about equal to the width of the circumferential faces on the cyclically moving pistons which are narrower than those on the uniformly rotating pistons, the latter faces being formed with radially open grooves circumferentially open in opposite directions on the axial levels of the intake and exhaust ports respectively, the aperture of the auxiliary chamber being on the level of the intake port.

United States Patent. 11 1 Sabet ROTARY PISTONENGINE WITH AUXILIARY CHAMBER ON ITS CASING [76] Inventor: Huschang Sabet,

Eduard-Pfeiffer-Strasse 67, 7

Stuttgart 1, Germany Notice: The portion of the term of this patent subsequent to Dec. 18, 1990, has been disclaimed. 1221 Filed: Mar. 13, 1973 1211 Appl. No.: 340,645

Related US. Application Data [63] Continuation-impart of Ser, Nos. 137,870, April 27, I971, Pat. No. 3,376,080, and Ser. No. 284,896 Aug. 30, 1972, Pat. NO. 3,779,215.

[30] A Foreign Application Priority Data *Dec. 31, 1974' Primary Examiner-William L. Freeh Assistant ExaminerMichae1 Koczo, Jr. Attorney, Agent, or Firm-Hans Berman; Kurt Kelman [57] ABSTRACT A rotary-piston engine in which two pairs ofpistons rotate in .a cylindrical casing, one pair rotating at uniform speed, the other at cyclically varying speed so that the pistons define expanding and contracting chambers therebetween, air of combustion is drawn through an intake port on one axial level, and combustion gases are discharged through an exhaust port on another level. A spark plug and a fuel injection nozzle are mounted in an auxiliary chamber outside the casing cavity which communicates with the auxiliary chamber through an aperture circumferentially divided by a partition, the total circumferential width of the aperture being about equal to the width of the circumferential faces on the cyclically moving pistons which are narrower than those on the uniformly rotating pistons, the latter faces being formed with radially open grooves circumferentially open in opposite directions on the axial levels of the intake and exhaust ber being on the level of the intake port.

3 Claims, 4 Drawing Figures PMENTEI] BEES] E374 SHEET 2 OF 2 ROTARY PISTON ENGINE WITH AUXILIARY CHAMBER ON ITS CASING This application is a continuation in part of the copending applications Ser. Nos. 137,870 and 284,896, respectively filed on Apr. 27, 1971, and Aug. 30, 1972 now US. Pat. Nos. 3,376,080 and 3,779,215.

This invention relates to rotary-piston, internalcombustion engines, and particularly to improvements in the rotary-piston engines disclosed and claimed in the afore-mentioned applications.

The engine type with which this invention is concerned has a casing which bounds a cavity of circular cross section at right angles to the casing axis. Two pairs of pistons are mounted in the cavity of simultaneous rotation about the axis, and each has a circumferential face sealingly engaging the casing during piston rotation. One pair of pistons rotates at uniform angular speed, and the other pair rotates at cyclically varying speed during operation of the engine, each piston of the one pair being interposed angularly between the pistons of the other pair, and its circumferential face being circumferentially wider than the faces of the pistons of the other pair. While the pistons rotate, they bound chambers of cylically varying volume in the casing cavity. The circumferential faces of the one pair of pistons are each formed with two axially spaced, raditween the ports and the chambers between the pistons.

It has now been found that engines of the type described can be .built more simply and operated more advantageously if provided with at least one auxiliary chamber which is located outside the casing cavity and whose interior space communicates with the casing cavity through an aperture on the axial level of the intake port or ports, the number of such chambers and apertures being equal to the number of intake ports. The apertures are approximately as wide circumferentially as the circumferential faces of the narrower pistons rotating at varying speed, and each aperture is circumferentially divided into two openings or slots by a partition member elongated in an axial direction.

The afore-described auxiliary chamberprovide more reliable ignition and complete combustion of the fuel mixture because the auxiliary chamber permits the engine to be operated with excess air of combustion. An adequately high and uniform temperature can be maintained in the auxiliary chamber or chambers so that ignition is achieved reliably even with a relatively lean fuel mixture. Local overheating, which tends to favor the formation of nitrogen oxides, is avoided.

' The total circumferential width of the aperture leading to the auxiliary chamber is preferably made substantially equal to the circumferential width of the cooperating faces of the narrower pistons, and also equal to the lands which separate each groove in the circumferential face of the wider pistons from the chamber opposite to that toward which the groove is open. Each auxiliary chamber thus is in practically continuous communication with a chamber between two pistons.

While each chamber sequentially passes through the four stages of a four-stroke cycle, the auxiliary chamber is practically always in communication with chambers which are in the compression stage of the cycle, and thus maintains its uniform temperature at all times.

mate mixing of the air with a liquid fuel injected into the auxiliary chamber, and uniform combustion of the portion of the fuel mixturein the auxiliary chamber.

The partition. memberhas the added function of preventing excessive heating of the circumferential face of a narrower piston, which momentarily stands still, or almost stands still, in front of the auxiliary chamber aperture, by the combustion gases in the auxiliary chamber, and of protecting the circumferential face from direct impact of the burning fuel mixture.

Turbulence in the auxiliary chamber may further be enhanced by suitably orienting the faces of the partition member and of the casing which circumferentially bound the trailing slot in each aperture. These faces preferably are inclined obliquely relative to the inner casing face in a circumferentialdirection away from the leading face, that is, in the direction of piston movement, and in a radially inward direction.

Depending on the mode of operation of the engine and the nature of thefuel employed, a spark plug, a glow head, and/or a fuel injection nozzle may be mounted in the auxiliary chamber.

The provision of one or more auxiliary chambers further permits a larger amount of fresh gas to be taken in for a predetermined compression ratio because the residual compression space and thus the amount of hot residual gases is substantially greater than in the absence of an auxiliary chamber.

The interior space of the auxiliary chamber has the approximate shape of a rectangle when viewed in section in a plane tangential to a cylinder coaxial with the casing which passes through the interior space of the auxiliary chamber. The axial width of the auxiliary chamber should be equal to the axial length of the associated slots for best results.

Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description of a preferred embodiment when considered in connectionwith the appended drawing in which:

FIG. 1 shows the casing of a rotary-piston internalcombustion engine of the invention in fragmentary radial section through an auxiliary chamber mounted F10. 4 shows the device of FIG. 3 in theotherdead center position of two pistons.

Referring now to the drawing in detail, there is shown only as much of a rotary-piston engine of the type more fully described inthe aforementioned copending applications and in US. Pat. No. 3,439,549 as is needed for an understanding of this invention.

The normally stationary, cylindrical casing l of the engine is double-walled for water-cooling, and the base portion 2 of an auxiliarychamber v4 is sealed into the casing wall circumferentially between an intake port 12 and an exhaust port 13 so that the base is flush with the cylindrical inner face of the casing in the cavity of the latter in which two pairs of pistons move about the easing axis.

The base 2 is outwardly sealed by a cover 3 into which a spark plug 6 and a fuel injection nozzle are set, and which is attached to the base by-bolts 3'. As is evident from joint consideration of FIGS. 1 and 2, the interior space of the chamber 4 is of approximately cylindrical shape about an axis spacedly parallel to the casing axis so that the chamber section is of rectangular shape, when viewed in the plane of FIG. 2 which is tangential to a cylinder about the casing axis passing through the chamber 4."

The chamber 4 communicates with the casing cavity through an aperture which is divided into twoislots 7,8 by a partitionZ' integral with the chamber base 2 and axially elongated.' As is indicated in FIG. 3 by a curved arrow, the direction of piston movement in the casing 1 of FIG. 1 is clockwise so that the slot 7 is leading and the slot 8 is trailing relative to the moving pistons.

faces bounding most of the trailing slot 8 are obliquely inclined relative to the inner circumferential face of the casing 1 in a radially inward direction and a circumferential direction away from the leading slot 7 and thus in the direction of piston movement. The orifice of the slot- 8 adjacent the casing cavity is flared. The axial length of each slot 7,8 is practically identical with the corresponding dimension of the interiror space of the chamber 4.

As is more fully explained in the afore-described earlier patent and patent applications, the engine has two pairs of pistons. One pair rotates about the casing axis at uniform angular velocity during operation of the engine, and the other pair rotates at cyclically varying velocity. The pistons of each pair are fixedly fastened to each other in diametrically opposite relationship. The pistons are partly shown in FIGS. 3 and 4.

The two pistons 10,10 of the uniformly rotating pair each flare radially outward from the axis towards a relatively wide circumferential face which is sealed to the inner cylindrical casing face and formed with a radially open groove 11,11 in the radial plane of the slots 7,8- and of the intake port 12 through which air of combus tion enters the casing 1. The grooves 11,11 are open in a clockwise circumferential direction, and each piston 10,10 is provided with a corresponding groove, not shown, in another radial plane through the exhaust port 13 of the casing l, the grooves in the plane of the exhaust port being open in a counterclockwise direction.

The circumferential width of the narrower circumferential face of each piston 9 and that of the land behind the groove 11,11 in the circumferential face of each piston 10,10 is about equal and barely wider than the overall circumferential width of the aperture connecting the chamber 4 with the casing cavity, as measured across the slots 7,8 and the partition 2'.

The chamber 4 thus communicates practically continuously with one of the four working chambers of cyclically varying capacity or volume which is circumferentially bounded between respective, approximately radially extending faces of a piston 9 and of a piston 10,10, each communicating chamber reaching its minimum volume after intake and prior to ignition, a position referred to herein as top dead-center by analogy with the corresponding piston condition in a reciprocating-piston engine.

As shown in FIG. 3, the exploding fuel mixture in the combustion chamber ahead of the piston 10 has pushed the non-illustrated smaller piston 9 towards the lower dead-center position, and communication between the partly illustrated leading working chamber and the auxiliary chamber 4 through the groove 11 has just been interrupted.

While the piston 10 moves on at a uniform rate from the position of FIG 3, the smaller piston 9 moves at a much smaller rate so as practically to stand still until the other bigger piston 10 can compress the air of combustion taken from the intake port 12 the groove 11 when the position of FIG. 4 is reached immediately preceding ignition.

While the illustrated engine relies on fuel injection and spark plug ignition, the advantages of this invention are not limited to the particular manner in which the fuel mixture is produced nor to the manner in which it is ignited. Thus, the combustible component may be mixed with the air of combustion outside the casing cavity and introduced through the nonillustrated intake port, and ignition may be brought about by a hot bulb if the engine operates in the Diesel cycle.

' It should be understood, therefore, that the foregoing disclosure relates only to a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

- tion of said engine, each piston of said one pair being interposed angularly between the pistons of the other pair and said circumferential face thereof having a circumferential width greater than the corresponding dimension of the pistons of the other pair, whereby chambers of cyclically varying volume are bounded by said pistons in said casing, said circumferential faces of the pistons of said one pair being each formed with two axially spaced, radially open grooves circumferentially open in respective opposite circumferential directions,

said casing being formed with an intake port and an exhaust port in axially spaced respective radial planes for communication with said grooves respectively during operation of said engine, the improvement which comprises:

a. an auxiliary chamber mounted on said casing outside said cavity and enclosing an interior space therein,

1. said casing being formed with an aperture substantially in the radial plane of said intake port and connecting the interior space of said chamber with said cavity,

2. the circumferential width of said aperture being substantially equal to the corresponding width of said circumferential face of each piston of said other pair; and

b. a partition member axially extending in said aperture and circumferentially dividing the same into two separate openings.

2. In an engine as set forth in claim 1, respective axial faces of said partition member and of said casing circumferentially bounding one of saidv openings and being obliquely inclined relative to the inner circumferential face of said casing in a radially inward direction and a circumferential direction away from the other opening.

3. In an engine as set forth in'claim 1, said interior space being of approximately rectangular shape in section in a plane tangential to a cylinder about said axis and through said space, the axial width of said shape being substantially equal to the axial length of said openings. 

1. In a rotary-piston, internal-combustion engine having an axis, a casing bounding a cavity of circular cross section about said axis, two pairs of pistons mounted on said cavity for simultaneous rotation about said axis, each piston having a circumferential face sealingly engaging said casing during said rotation, one of said pairs rotating at uniform angular speed and the other pair rotating at cylically varying angular speed during operation of said engine, each piston of said one pair being interposed angularly between the pistons of the other pair and said circumferential face thereof having a circumferential width greater than the corresponding dimension of the pistons of the other pair, whereby chambers of cyclically varying volume are bounded by said pistons in said casing, said circumferential faces of the pistons of said one pair being each formed with two axially spaced, radially open grooves circumferentially open in respective opposite circumferential directions, said casing being formed with an intake port and an exhaust port in axially spaced respective radial planes for communication with said grooves respectively during operation of said engine, the improvement which comprises: a. an auxiliary chamber mounted on said casing outside said cavity and enclosing an interior space therein,
 1. said casing being formed with an aperture substantially in the radial plane of said intake port and connecting the interior space of said chamber with said cavity,
 2. the circumferential width of said aperture being substantially equal to the corresponding width of said circumferential face of each piston of said other pair; and b. a partition member axially extending in said aperture and circumferentially divIding the same into two separate openings.
 2. In an engine as set forth in claim 1, respective axial faces of said partition member and of said casing circumferentially bounding one of said openings and being obliquely inclined relative to the inner circumferential face of said casing in a radially inward direction and a circumferential direction away from the other opening.
 2. the circumferential width of said aperture being substantially equal to the corresponding width of said circumferential face of each piston of said other pair; and b. a partition member axially extending in said aperture and circumferentially divIding the same into two separate openings.
 3. In an engine as set forth in claim 1, said interior space being of approximately rectangular shape in section in a plane tangential to a cylinder about said axis and through said space, the axial width of said shape being substantially equal to the axial length of said openings. 